This invention relates to disk drives, and in particular relates to metal laminates for disk drives comprising resin disposed on one metal layer or between two metal layers.
Disk drives store information on concentric, recorded tracks written on one or more rotatable magnetic recording disks. A magnetic head or transducer element is provided for each such disk, and moves from track to track, to either read previously stored information or to record information on the magnetic tracks (“read”-“write”, respectively). The electromagnetic transducer typically is carried in a slider body mechanism that is supported over the surface of a rotating disk by a self-acting, hydrodynamic air bearing. The slider body/transducer combination is referred to collectively as a “head”, and it is attached to a suspension assembly that suspends and loads the head toward the disk surface. The suspension assembly is in turn connected to a rotary or linear actuator that controllably moves the head from track to track on the disk, in response to electrical signals generated by controlling circuitry.
The suspension assembly may comprise a single element or several connected elements. Generally the suspension assembly comprises a structural element and a circuit element. The structural element, sometimes known as a load beam, provides physical support for the head and the circuit element electronically connects the head to the remainder of the disk drive. In some instances the structural element is configured such that it also functions as the circuit element.
There is a continuing trend towards increasing density in disk drives. Continuing improvements in magnetic recording media, head designs, and control circuitry have permitted data tracks to become narrower and closer together, requiring lighter and more selectively flexible suspension assemblies. Additionally, as data retrieval becomes faster, disks spin at increasing speeds. The increased speeds cause vibrational effects (also known as windage effects). It is becoming increasingly important for the suspension assembly to have damping capability over the disk operating temperature and frequency ranges in addition to being lightweight and selectively flexible.
Laminates are an attractive material for suspension assemblies. Laminates comprising a resin layer and at least one metal layer are widely used in the electronic industry for applications such as circuit boards and components used in disk drives. Laminates are generally required to have high bond strength (peel strength) and high dimensional stability. Some laminate applications require additional characteristics. For example, laminates used in disk drive applications must have low levels of ionic contamination, low melamine levels, contain no silicone, low levels of organic tin (preferably none), and low levels of organic out-gassing.
Chemical etching and plasma etching techniques can be used to achieve the desired bending characteristics of laminates (selective flexibility). The removal of metal by chemical etching and the removal of resin by either chemical etching or plasma etching from selected locations of the laminate and the resultant variations in laminate thickness both reduce the weight of the laminate and change its dynamic characteristics. Etching must have a high rate, be as clean as possible, and must have minimum undercuts to achieve the desired design density.
There is a need in the art for suspension assemblies and laminates with improved properties, particularly damping capability under disk drive operating conditions (temperature and frequency) and good chemical and/or plasma etchability.